topic Cutting over iSCSI LUNs between filers in VMware Solutions Discussions

Cutting over iSCSI LUNs between filers

mattmusgrove1 — Thu, 05 Jun 2025 05:46:12 GMT

I need to cutover from one FAS to another, a task I have accomplished many times before using SnapMirror to transfer the data. Using OnTap 7.3.7

Previously I have only had to cutover CIFS and NFS, however on this occasion I also have two iSCSI LUNs.

How does the new FAS recognise the LUNs which were created on the original FAS? I assume I will also need to configure initiator groups.

I can't see any config files in my etc directory in the root volume which relate to iscsi.

Can someone advise on the right way to migrate iSCSI LUNs between filers?

Re: Cutting over iSCSI LUNs between filers

billshaffer — Tue, 07 Jan 2014 16:23:31 GMT

I have done this before. Snapmirror the data, and the new controller will see the luns with "lun show". You're right, you'll need to configure the inititator groups, etc.

One caveat - luns have a serial number that I don't believe is copied with snapmirror. Some applications (Exchange comes to mind) are picky about this serial number; they won't let you use data on a different lun serial, even though it's the same drive letter. List the existing lun's serial with "lun serial <lun_path>", and set the new lun's serial with "lun serial <lun_path> <serial>".

Bill

Re: Cutting over iSCSI LUNs between filers

nitish — Tue, 07 Jan 2014 18:22:07 GMT

Unmount iSCSI LUNs on hosts
Shut down iSCSI on filer
o iscsi stop;iscsi status
Perform snapmirror update
Perform snapmirror break
Make a copy of iscsi nodename from the orignal source filer
Modify nodename <dfiler> iscsi nodename
o iscsi nodename [<new_nodename>]
o iSCSI target nodename: iqn.1992-08.com.netapp:sn.118055087
Create igroups on filer and verify initiators are logged in
o igroup create -i -t windows <igroup> <iqn>
igroup show –v
Note the orignal LUNs Serial number
Change LUNs to original serial number
o priv set advanced;lun offline <LUN>
lun serial <LUN> Hnd5CZjW3OrO
lun online <LUN>
Map LUNs with iSCSI initiator groups and verify
o lun map <LUN> <igroup> <LUN_id>
lun show -v <LUN>
Check to see if hosts can mount LUNs. If not, reboot and re-verify
o Restart iSCSI service on hosts if necessary
o Remount iSCSI LUNs on hosts
o iscsi session show (used to verify iSCSI session)

I found the above steps to be a cleaner way to migrate LUNs to new filer.

Re: Cutting over iSCSI LUNs between filers

aborzenkov — Tue, 07 Jan 2014 19:19:26 GMT

Yes, you will need to manually create igroups and mapping on destination filer - they are not replicated. Also LUN serial numbers will change - this may be problem depending on host OS (e.g. VMware will not mount them by default).